Dual syringe fluid pump

ABSTRACT

A dual syringe fluid pump ( 100, 200, 300, 400 ) includes a motor ( 110, 210, 310, 410 ) with a rotatable shaft ( 112, 212, 312, 412 ), a first syringe ( 120   a,    220   a,    320   a,    420   a ) with a first syringe plunger ( 122   a,    222   a,    322   a,    422   a ) coupled to the rotatable shaft ( 112, 212, 312, 412 ), and a second syringe ( 120   b,    220   b,    320   b,    420   b ) with a second syringe plunger ( 122   b,    222   b,    322   b,    422   b ) coupled to the rotatable shaft ( 112, 212, 312, 412 ). The motor ( 110, 210, 310, 410 ) rotates the rotatable shaft ( 112, 212, 312, 412 ) to simultaneously move the first syringe plunger ( 122   a,    222   a,    322   a,    422   a ) and the second syringe plunger ( 122   b,    222   b,    322   b,    422   b ) and at least one of the syringes ( 120   a,b,    220   a,b,    320   a,b,    420   a,b ) is adapted to convert the rotation of the rotatable shaft ( 112, 212, 312, 412 ) to a linear movement of at least one of the syringe plungers ( 122   a,b,    222   a,b,    322   a,b,    422   a,b ).

TECHNICAL FIELD

The embodiments described below relate to, fluid control devices, and more particularly, to dual syringe fluid pumps.

BACKGROUND

Pumps are able to continuously dispense fluid that has desired properties. The desired properties can include pressure and flow rates. Some applications also require that the properties be within a specified range. That is, the pumps may be required to meet precision and accuracy specifications. Unfortunately, pumps that are able to continuously dispense fluids are often unable to meet theses specifications. In addition, pumps that are able to meet the precision and accuracy specifications are usually unable to meet these specifications over large number of dispenses. For example, some prior art pumps can only be used for a single dispensing of fluids, such as dual syringe insulin pumps. Pumps that are able to continuously dispense fluids in precise and accurate amounts can have complex designs that utilize gears, multiple motors, and other devices.

Complex pump designs can have disadvantages such as increased costs and lack of repeatability over large number of cycles or dispenses due to design tolerances accumulating over several parts. Accumulated design tolerances can cause large overall manufacturing variations in the pumps or syringes. This large tolerance can cause the fluid dispensed from the pump to vary considerably on a pump to pump basis. The variations can also cause the fluid dispensing to lack precision. That is, the amount dispensed from the pump can vary between dispenses. Such variation in the amount of dispensed fluid is undesirable for applications that require precision and accuracy. For example, the fluid can be syrup dispensed into a mixture that is bottled for consumers who might be able to detect even a slight change in flavor. Although pumps can sometimes be calibrated or adjusted after being manufactured, such adjustability and calibration can lead to further complexity. Complex designs can also adversely affect the reliability of the pumps.

For complex pumps, precise fluid dispensing can be ensured by manufacturing parts to tight tolerances. However, such parts are prohibitively expensive. In addition, due to the complexity of the designs utilizing multiple motors and complex dispensing assemblies, the cumulative costs of the individual parts can be even more prohibitive. Moreover, the complex designs generally have a higher failure rate which can prevent complex assemblies from being used in industries that require components to meet reliability standards. (e.g., an overall assembly failure rate that is below an industry specified rate.)

Accordingly, there is a need for a less complex dual syringe fluid pump for dispensing precise and accurate amounts of fluid.

SUMMARY

A dual syringe fluid pump provided that is comprised of a motor with a rotatable shaft. According to an embodiment, the dual syringe fluid pump further comprises a first syringe with a first syringe plunger coupled to the rotatable shaft and a second syringe with a second syringe plunger coupled to the rotatable shaft. The motor rotates the rotatable shaft to simultaneously move the first syringe plunger and the second syringe plunger and at least one of the syringes is adapted to convert a rotation of the rotatable shaft to a linear movement of at least one of the syringe plungers.

A method of forming a dual syringe fluid pump is provided. According to an embodiment, the method comprises forming a motor with a rotatable shaft, forming a first syringe with a first syringe plunger and coupling the first syringe plunger to the rotatable shaft, forming a second syringe with a second syringe plunger and coupling the second syringe plunger to the rotatable shaft. The method further comprises adapting the motor to rotate the rotatable shaft to simultaneously move the first syringe plunger and the second syringe plunger and adapting at least one of the syringes to convert a rotation of the rotatable shaft to a linear movement of at least one of the syringe plungers.

A method of using a dual syringe fluid pump is provided. According to an embodiment, the method comprises providing a dual syringe fluid pump comprised of a motor with a rotatable shaft, a first syringe with a first syringe plunger coupled to the rotatable shaft, and a second syringe with a second syringe plunger coupled to the rotatable shaft. The method further comprises providing fluid from a fluid source to the first syringe and the second syringe, and rotating the rotatable shaft and converting the rotation of the rotatable shaft to a linear movement of at least one of the syringe plungers to dispense fluid from the first syringe while simultaneously aspirating fluid into the second syringe from the fluid source.

Aspects

According to an aspect, a dual syringe fluid pump (100, 200, 300, 400) comprises a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412), a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) coupled to the rotatable shaft (112, 212, 312, 412), and a second syringe (120 b, 220 b, 320 b, 420 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) coupled to the rotatable shaft (112, 212, 312, 412), wherein the motor (110, 210, 310, 410) rotates the rotatable shaft (112, 212, 312, 412) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) and at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) is adapted to convert a rotation of the rotatable shaft (112, 212, 312, 412) to a linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b).

Preferably, at least one of the syringes (120 a,b) further comprises a barrel (124 a) with a center bore (124 cb) having a profile that prevents rotation of the at least one of the syringe plungers (122 a,b) to convert the rotation of the rotatable shaft (112) to the linear movement of the at least one of the syringe plungers (122 a,b).

Preferably, the dual syringe fluid pump (200) further comprises a constraint (252) and an aperture (225) in the syringe plunger (222 a) wherein the constraint (252) is coupled to the motor (210) and slidably coupled to the aperture (225) to prevent a rotation of the at least one of the syringe plungers (222 a,b) such that rotation of the rotatable shaft (212) is converted to the linear movement of at least one of the syringe plungers (222 a,b).

Preferably, the motor (110, 210, 310, 410) is further adapted to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) and dispense fluid from the second syringe (120 b, 220 b, 320 b, 420 b).

Preferably, the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) further comprises a first valve (126 ai,bi 226 ai,bi 326 ai,bi 426 ai,bi) adapted to allow fluid to flow into the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b), and a second valve (126 ao,bo, 226 ao,bo, 326 ao,bo, 426 ao,bo) adapted to allow fluid to flow out of the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b).

Preferably, the first syringe plunger (122 a) is coupled to a first end of the rotatable shaft (112), the second syringe plunger (122 b) is coupled to a second end of the rotatable shaft (112), and the rotatable shaft (112) extends through the motor (110) from the first syringe (120 a) to the second syringe (120 b).

Preferably, the rotatable shaft (112) rotates coaxially with the linear movement of at least one of the syringe plungers (122 a,b).

Preferably, the dual syringe fluid pump (400) further comprises a coupler (412 b) coupled to the rotatable shaft (412) wherein the rotatable shaft (412) is adapted to rotate the coupler (412 b) to move the first syringe plunger (412 a) to dispense fluid from the first syringe (420 a) and move the second syringe plunger (422 b) to aspirate fluid into the second syringe (420 b).

According to another aspect, a method of forming a dual syringe fluid pump (100, 200, 300, 400) comprises forming a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412), forming a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) and coupling the first syringe plunger (122 a, 222 a, 322 a, 422 a) to the rotatable shaft (112, 212, 312, 412), forming a second syringe (120 b, 220 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) and coupling the second syringe plunger (122 b, 222 b, 322 b, 422 b) to the rotatable shaft (112, 212, 312, 412), and adapting the motor (110, 210, 310, 410) to rotate the rotatable shaft (112, 212, 312, 412) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) and adapting at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) to convert a rotation of the rotatable shaft (112, 212, 312, 412) to a linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b).

Preferably, the forming the at least one of the syringes (120 a,b) further comprises forming a barrel (124 a) with a center bore (124 cb) having a profile that prevents rotation of the at least one of the syringe plungers (122 a,b) to convert the rotation of the rotatable shaft (112) to the linear movement of the at least one of the syringe plungers (122 a,b).

Preferably, the forming the at least one of the syringes (120 a,b) further comprises forming a barrel (124 a) with a center bore (124 cb) having a profile that prevents rotation of the at least one of the syringe plungers (122 a,b) to convert the rotation of the rotatable shaft (112) to the linear movement of the at least one of the syringe plungers (122 a,b).

Preferably, the method of forming the dual syringe fluid pump (200) further comprises forming a constraint (252), forming an aperture (225) in the syringe plunger (222 a), coupling the constraint (252) to the motor (210), and slidably coupling the constraint (252) to the aperture (225) to prevent a rotation of the at least one of the syringe plungers (222 a,b) such that rotation of the rotatable shaft (212) is converted to the linear movement of at least one of the syringe plungers (222 a,b).

Preferably, the method of forming the dual syringe fluid pump (100, 200, 300, 400) further comprises adapting the motor (110, 210, 310, 410) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) and dispense fluid from the second syringe (120 b, 220 b, 320 b, 420 b).

Preferably, the forming the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) further comprises forming and adapting a first valve (126 ai,bi 226 ai,bi 326 ai,bi 426 ai,bi) to allow fluid to flow into the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) and forming and adapting an second valve (126 ao,bo, 226 ao,bo, 326 ao,bo, 426 ao,bo) to allow fluid to flow out of the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b).

Preferably, the method of forming the dual syringe fluid pump (100, 200, 300) further comprises coupling the first syringe plunger (122 a, 222 a, 322 a) to a first end of the rotatable shaft (112, 212, 312), coupling the second syringe plunger (122 b, 222 b, 322 b) to a second end of the rotatable shaft (112, 212, 312), and extending the rotatable shaft (112, 212, 312) through the motor (110, 210, 310) from the first syringe (120 a, 220 a, 320 a) to the second syringe (120 b, 220 b, 320 b).

Preferably, the method of forming the dual syringe fluid pump (100, 200, 300, 400) further comprises adapting the rotatable shaft (112, 212, 312, 412) to rotate coaxially with the linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 b, 422 b).

Preferably, the method of forming the dual syringe fluid pump (400) further comprises forming and coupling a coupler (412 b) to the rotatable shaft (412), and adapting the rotatable shaft (412) to rotate the coupler (412 b) to move the first syringe plunger (422 a) to dispense fluid from the first syringe (420 a) and move the second syringe plunger (422 b) to aspirate fluid into the second syringe (420 b).

Preferably, the method of forming the dual syringe fluid pump (100, 200, 300, 400) further comprises selecting a motor (110, 210, 310, 410) rotation to a syringe plunger (122 a,b 222 a,b 322 a,b 422 a,b) displacement ratio.

According to another aspect, a method of using a dual syringe fluid pump (100, 200, 300, 400) comprises providing a dual syringe fluid pump (100, 200, 300, 400) comprised of a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412), a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) coupled to the rotatable shaft (112, 212, 312, 412), and a second syringe (120 b, 220 b, 320 b, 420 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) coupled to the rotatable shaft (112, 212, 312, 412), providing fluid from a fluid source (370, 470) to the first syringe (120 a, 220 a, 320 a, 420 a) and the second syringe (120 b, 220 b, 320 b, 420 b), and rotating the rotatable shaft (112, 212, 312, 412) with the motor (110, 210, 310, 410) and converting the rotation of the rotatable shaft (112, 212, 312, 412) to the linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b) to dispense fluid from the first syringe (120 a, 220 a, 320 a, 420 a) while simultaneously aspirating fluid into the second syringe (120 b, 220 b, 320 b, 420 b) from the fluid source (370, 470).

Preferably, the method of using the dual syringe fluid pump (100, 200, 300, 400) further comprises rotating the rotatable shaft (112, 212, 312, 412) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) from the fluid source (370, 470) while simultaneously dispensing fluid from the second syringe (120 a, 220 b, 320 b, 420 b).

Preferably, the method of using the dual syringe fluid pump (100, 200, 300, 400) further comprises dispensing fluid from the first syringe (120 a, 220 a, 320 a, 420 a) and the second syringe (120 b, 220 b, 320 b, 420 b) to a fluid supply conduit (390, 490) in a substantially continuous fluid flow.

BRIEF DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element on all drawings. It should be understood that the drawings are not necessarily to scale.

FIG. 1 shows a perspective view of a dual syringe fluid pump 100 according to an embodiment.

FIG. 2 shows a plan end view of the dual syringe fluid pump 100 taken at section 2-2 shown in FIG. 1.

FIG. 3 shows another perspective view of the dual syringe fluid pump 100.

FIGS. 4a and 4b show transparent plan views of the barrel 124.

FIGS. 5a -5c show plan and perspective views of the syringe plunger 122.

FIG. 6 shows a perspective view of a dual syringe fluid pump 200 according to another embodiment.

FIG. 7 shows a detailed perspective view of the dual syringe fluid pump 200.

FIGS. 8a and 8b show schematic views of a dual syringe fluid pump 300 according to another embodiment.

FIG. 9 shows a side plan view of a dual syringe fluid pump 400 according to an embodiment.

FIGS. 10a and 10b show schematic representations of the dual syringe fluid pump 400 according to an embodiment.

DETAILED DESCRIPTION

FIGS. 1-10 b and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of embodiments of a dual syringe fluid pump. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the present description. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the dual syringe fluid pump. As a result, the embodiments described below are not limited to the specific examples described below, but only by the claims and their equivalents.

FIG. 1 shows a perspective view of a dual syringe fluid pump 100 according to an embodiment. As shown, the dual syringe fluid pump 100 includes a motor 110 that is coupled to a first syringe 120 a and a second syringe 120 b. The first syringe 120 a is shown in a transparent view for clarity. The syringes 120 a,b include syringe plungers 122 a,b (the first syringe plunger 122 a is shown). The syringes 120 a,b also include barrels 124 a,b that encloses the syringe plungers 122 a,b. The barrels 124 a,b include a center bore 124 cb. Inlet 126 ai,bi and outlet valves 126 ao,bo are coupled to the barrels 124 a,b. The first inlet valve 126 ai is not shown in FIG. 1 for clarity. The outlet valves 126 ao,bo allow fluid in the dual syringe fluid pump 100 to be dispensed by the syringes 120 a,b. The inlet valves 126 ai,bi allow fluids to be aspirated into the syringes 120 a,b as will be described in more detail in the following.

FIG. 2 shows a plan end view of the dual syringe fluid pump 100 taken at section 2-2 shown in FIG. 1. As can be seen, the syringe plungers 122 a,b have profiles that interface with profiles in the barrels 124 a,b. The interfaced profile is shown as oval shaped with flat sides. As will be described in more detail in the following with reference to FIG. 4a -5 c, the interfaced profiles prevent the rotation of the syringe plungers 122 a,b. Preventing the plungers 122 a,b from rotating can convert the motor 110 rotation to a linear displacement of the syringe plungers 122 a,b. The motor 110 can also be adapted to simultaneously move the syringe plungers 122 a,b as will be described in more detail in the following.

FIG. 3 shows another perspective view of the dual syringe fluid pump 100. The first syringe 120 a is shown with an exploded perspective view for clarity. The motor 110 includes a rotatable shaft 112. The rotatable shaft 112 is coupled to the syringe plungers 122 a,b. The first syringe plunger 122 a has two O-rings 123. Between the motor 110 and the first syringe 120 a are pins 140. The pins 140 align and couple the motor 110 with the collars 130 a,b. A set screw 132 is employed to couple the collars 130 a,b with the syringe barrels 124 a,b although any suitable fastening means can be employed. The collars 130 a,b also couple the syringes 120 a,b to the motor 110.The rotatable shaft 112 is shown as a through axis shaft that extends through the center of the motor 110. However, in alternative embodiments, more than one shaft can be employed (e.g., with a coupling or the like). The shaft 112 can also be located somewhere other than the center of the motor 110. As shown, the syringe plungers 122 a,b are coupled to a first and second distal ends of the rotatable shaft 112.

The motor 110 is adapted to rotate the rotatable shaft 112 to simultaneously move the syringe plungers 122 a,b. The motor 110 can therefore simultaneously dispense fluid from the first syringe 120 a and aspirate fluid into the second syringe 120 b. The rotation can also cause a torque on the plunger 122 a that, if not prevented, could cause the plunger 122 a to rotate. The following discusses how the plunger 122 a,b is prevented from rotating.

FIGS. 4a and 4b show transparent plan views of the barrel 124. FIG. 4a shows a side plan view of the barrel 124 and FIG. 4b shows an end plan view of the barrel 124. The barrel 124 is shown as having a slot 124 ss that is adapted to receive the set screw 132. Also shown are the center bore 124 cb, an inlet bore 124 ib, and an outlet bore 124 ob. The center bore 124 cb is coupled to the inlet bore 124 ib and the outlet bore 124 ob via an inlet tap 124 it and an outlet tap 124 ot. As can be seen, the center bore 124 cb has a shaped profile. This shaped profile can interface with the syringe plunger 122.

FIGS. 5a -5c show plan and perspective views of the syringe plunger 122. The syringe plunger 122 includes a face rib 122 fr, a center rib 122 cr, and a rear rib 122 rr. The syringe plunger 122 also includes two O-ring slots 122 s 1,s 2. Although two O-ring slots 122 s 1,s 2 are shown, more or fewer O-ring slots may be employed in alternative embodiments. The O-ring slots 122 s 1,s 2 are adapted to receive and hold the O-rings 123 described with reference to FIG. 3. As can be seen in FIGS. 5 and 5 c, the plunger 122 a has a shaped profile.

Referring to FIGS. 4a-5c as well as FIG. 2, the center bore 124 cb profile can interface with the syringe plunger 122's profile. The interfaced profiles are shown as oval shaped with flat sides although other appropriately shaped profiles can be employed. The interfaced profiles provide a fluid seal that can prevent leakage of fluid past the O-rings 123 shown in FIG. 3. This allows the fluid dispensed from and aspirated into the syringes 120 to be precise, accurate, and repeatable. For example, if the fluid leakage past the O-rings 123 is prevented, the volume of fluid dispensed may not vary between each dispensing due to leakage. The volume of the fluid dispensed can therefore be more precise.

The interfaced profiles also prevent the plunger 122 a,b from rotating when the motor 110 rotates the rotatable shaft 112. For example, the rotatable shaft 112 can rotate to move the plunger 112 a away from the motor 110. Friction between the rotatable shaft 112 and the plunger 112 a can therefore apply a torque to the plunger 112 a. The interfaced profiles apply reactive forces to the plunger 112 a that counter the torque. The reactive forces prevent the plunger 112 a from rotating. Similar results can be obtained from other profiles shapes such as square shaped profiles with rounded corners or the like. As an alternative to the shaped interfaced profiles, other embodiments can employ constraints to prevent the plunger from rotating, which are described in the following with reference to FIGS. 6 and 7.

FIG. 6 shows a perspective view of a dual syringe fluid pump 200 according to another embodiment. The dual syringe fluid pump 200 is shown with an exploded view of the first syringe 220 a. The dual syringe fluid pump 200, similar to the dual syringe fluid pump 100, includes a motor 210 that is coupled to a first syringe 220 a and a second syringe 220 b. A collar 250 is between the motor 210 and the first syringe 220 a. The syringes 220 a,b includes syringe plungers 222 a,b slidably disposed inside barrels 224 a,b (only the first syringe plunger 222 a is shown). In contrast to the syringe plunger 112 a shown in FIGS. 1-5 c, the syringe plunger 222 a has a circular shape. O-rings 223 are disposed around the syringe plunger 222 a. The barrel 224 a has a center bore 224 cb, an outlet bore 226 ao, an inlet bore 226 ai. The center bore 224 cb is coupled to the inlet valve 226 ai and the outlet valve 226 ao. The syringe 220 also includes a nut 225 that is coupled to syringe plunger 222 a. The barrel 224 a also includes a nut bore 227. The nut 225 is adapted to fit into the nut bore 227. The nut 225 also has apertures 225′ that are slidably coupled to constraints 252. Although two apertures 225′ and constraints 252 are shown, more or fewer may be employed in alternative embodiments.

FIG. 7 shows a detailed transparent perspective view of the dual syringe fluid pump 200. For clarity, the motor 210 and the first syringe 220 a are shown in a transparent assembled view without the second syringe 220 b. The syringe plunger 222 a is slidably disposed in the center bore 224 cb. The center bore 124 cb is coupled to the inlet bore 124 ib and the outlet bore 124 ob via an inlet tap 124 it and an outlet tap 124 ot. The constraints 252 are coupled to the barrel 224 a. The nut 225 is slidably disposed inside the nut bore 227.

The nut 225 can move linearly along the length of the constraints 252. The constraints 252 prevent the rotation of the syringe plunger 222 a. For example, when the motor 210 rotates the rotatable shaft 212, the constraints 252 oppose a rotational torque on the syringe plunger 222 a. This can prevent the rotation of the syringe plunger 222 a thereby converting the rotation of the rotatable shaft 212 to a linear movement and displacement of the syringe plunger 222 a within the center bore 224 cb. Accordingly, the syringe plunger 222 a can have a profile (e.g., circular) that does not prevent the rotation of the syringe plunger 222 a.

With reference to FIGS. 1-7, the motor 110, 210 is a direct drive motor although any suitable motor, such as a stepper motor, can be employed. In the embodiment shown, the motor 110, 210 can also include an encoder that detects the rotation position of the motor 110, 210. The motor 110, 210 is adapted to simultaneously move the syringe plungers 122 a,b, 222 a,b in the barrels 124 a,b 224 a,b. The motor 110, 210 is disposed between and coupled to the syringes 120 a,b 220 a,b. However, in alternative embodiments, such as those shown in FIGS. 9-10 b, the motor can be coupled to syringes in different configurations or locations. The motor 110, 210 is adapted to receive a command from a controller (see FIGS. 8a-8b ) that instructs the motor 110, 210 to rotate the rotatable shaft 112, 212 a desired amount. The desired amount can be in units of radians, steps, or the like. The encoder in the motor 110, 210 can also send information to the controller. As will be explained in more detail in the following, the desired rotation can correspond with the amount of fluid that is dispensed from and aspirated into the syringes 120 a,b 220 a,b.

The motor 110, 210 is adapted to rotate the rotatable shaft 112, 212 to simultaneously move the syringe plungers 122 a,b 222 a,b. The motor 110, 210 can therefore simultaneously dispense fluid from the first syringe 120 a, 220 a and aspirate fluid into the second syringe 120 b, 220 b. For example, in the embodiment shown, the motor 110, 210 rotates the rotatable shaft 112, 212 which moves the first syringe plunger 122 a, 222 a away from the motor 110, 210. The rotation also moves the second syringe plunger 122 b, 222 b towards the motor 110, 210. In this exemplary movement, fluid is dispensed from the first syringe 120 a, 220 a via the first outlet valve 126 ao, 226 ao and aspirated into the second syringe 120 b, 220 b via the second inlet valve 126 bi, 226 bi. Rotating the shaft 112, 212 in the opposite direction causes fluid to be aspirated into the first syringe 120 a, 220 a and fluid to be dispensed from the second syringe 120 b, 220 b.

The rotatable shaft 112, 212 is a lead screw adapted to linearly move the syringe plungers 122 a,b 222 a,b according to a rotation-to-displacement ratio. That is, each unit of rotation of the rotatable shaft 112, 212 corresponds to a displacement of the plungers 122 a,b 222 a,b. Although the rotatable shaft 112, 212 is a lead screw shaft with threads, any appropriate means of converting the shaft 112, 212 rotation to a linear movement and displacement of the syringe plungers 122, 222 can be employed. In the embodiment shown, the rotatable shaft 112, 212 is comprised of screw threads with a selected rotation-to-displacement ratio, which can be expressed as number of threads per unit length. Therefore, when the motor 110, 210 receives a command from a controller (see FIGS. 8a-8b ) to rotate a desired amount, the rotatable shaft 112, 212 is adapted to move the syringe plungers 122, 222 a desired displacement length. In the embodiment shown, the rotatable shaft 112, 212 moves linearly along the center axis of the motor 110, 210 to move the plungers 122, 222.

Converting the shaft 112, 212 rotation to a linear movement and displacement of the syringe plungers 122, 222 allows the motor 110, 210 to dispense from and aspirate fluid into the syringes 120, 220. The motor 110, 210 can also dispense fluid in a substantially continuous manner, as will be described in the following with reference to FIGS. 8a -8 b.

FIGS. 8a and 8b show a schematic view of a dual syringe fluid pump 300 according to another embodiment. The dual syringe fluid pump 300 is a schematic representation of the dual syringe fluid pumps 100, 200 described with reference to FIGS. 1 to 7. For example, the syringes 320 a,b represent the syringes 120, 220 described with reference to FIGS. 1 to 7. Accordingly, description of features shown in FIGS. 8a-8b can correspond to features described with reference to FIGS. 1-7. However, the dual syringe fluid pump 300 can also be a schematic representation of other embodiments.

As shown, the dual syringe fluid pump 300 includes a motor 310 that is coupled to a first syringe 320 a and a second syringe 320 b. The motor 310 is adapted to dispense fluid from and aspirate fluid into the syringes 320 a,b. Also shown is a controller 360 that is electrically coupled to the motor 310 and the syringes 320 via signal lines 362 a,b. The signal lines 362 a,b are adapted to carry signals between the controller 360 and syringes 320 a,b which can have sensors 320 as,bs. A fluid source 370 and a fluid supply conduit 390 is also shown. The fluid source 360 is fluidly coupled to the syringes 320 a,b. The fluid supply conduit 390 is a conduit that can be coupled to equipment that uses fluid dispensed by the fluid pump 300.

Arrows indicating movement are also shown in FIGS. 8a and 8b . The direction of the plunger 322 a,b displacement is represented by an arrow in the motor 310. The direction of the fluid flow dispensed from and aspirated into the syringes 320 a,b is shown by arrows proximate the valves 326. For example, the arrow proximate the first syringe outlet valve 326 ao indicates that the fluid is being dispensed from the first syringe 320 a. The arrow proximate the second syringe inlet valve 326 bi shown in FIG. 8a indicates that fluid is being aspirated into the second syringe 320 b. The arrow in the motor 310 in FIG. 8a indicates that the syringe plunger 322 a in the first syringe 320 a is moving away from the motor 310. The syringe plunger 322 b is moving towards the motor 310.

The displacement direction of the syringe plungers 322 a,b shown in FIG. 8a dispenses fluid from the first syringe 320 a via the outlet valve 326 ao. This displacement also aspirates fluid into the second syringe 320 b via the inlet valve 326 bi. The first syringe inlet valve 326 ai and the second syringe outlet valve 326 bo are closed due to the pressure in the syringes 320 a,b. A relatively low pressure in the second syringe 320 b prevents the second outlet valve 320 bo from opening. A relatively high pressure in the first syringe 320 a prevents the first inlet valve from opening. In FIG. 8b , the displacement direction of the syringe plungers 322 a,b shown as moving in a direction opposite the direction shown in FIG. 8 a.

The dual syringe fluid pumps 100-300 described with reference to FIGS. 1-8 b have rotatable shafts 112-312 in a through axis configuration. The through axis configuration allows the motor 110-310 to simultaneously move the first syringe plunger 120 a-320 a and the second syringe plunger 120 b-320 b. However, other embodiments of the dual syringe fluid pump can simultaneously move the syringe plungers 122 a,b-322 a,b without using the through axis configuration, as will be described in the following with reference to FIGS. 9-10 b.

FIG. 9 shows a side plan view of a dual syringe fluid pump 400 according to an embodiment. As shown, the motor 410 is disposed on one side of the dual syringe fluid pump 400. The syringes 420 a,b are arranged in a parallel configuration. The syringes 420 a,b have syringe plungers 422 a,b. The dual syringe fluid pump 400 can have inlet and outlet valves 426. In the embodiment shown, the first syringe 420 a has an inlet valve 426 ai and an outlet valve 426 ao. The second syringe 420 b has an inlet valve 426 bi and an outlet valve 426 bi. Similar to the embodiments described in the foregoing, the motor 410 has a rotatable shaft 412. The rotatable shaft 412 is shown with an encoder 412 a. The rotatable shaft 412 is coupled to the syringe plungers 422 a,b via a coupler 412 b. The coupler 412 b is a worm gear coupler although other couplers can be employed in alternative embodiments. The syringe plungers 422 a,b have grooved portions 422 at,bt (e.g., cam locks or the like) that are coupled to the coupler 412 b.

Due to the parallel configuration of the syringes 420 a,b the plungers 422 a,b in the syringes 420 a,b have parallel stroke axes. However, in alternative embodiments, the stroke axes can be oriented in different directions. In the embodiment shown, the syringe plungers 422 a,b move away from the motor 410 to dispense fluids from the first syringe 420 a. The syringe plungers 422 a,b move towards the motor 410 to aspirate fluid into the plungers 420 a,b. Accordingly, the motor 410 can move the syringe plungers 422 a,b to dispense fluid from and aspirate fluid into the syringes 420 a,b.

The motor 410 rotates the coupler 412 b to move the syringe plungers 422 a,b in opposite directions. The rotating coupler 412 b is engaged with the grooved portions 412 at,bt. In the embodiment shown, the grooved portions 412 at,bt have grooves with opposing orientations. For example, the first grooved portion 412 at can have left hand twisted grooves. The second thread portion 412 bt can have right hand twisted grooves. When the coupler 412 b rotates, the opposing orientations of the grooves causes the plungers 422 a,b to move in opposite directions. For example, the first plunger 422 a can move away from the motor 410 while the second plunger 422 b simultaneously moves toward the motor 410. To reverse the directions of the plungers 422 a,b the motor 410 reverses the rotation of the rotatable shaft 412. The motor 410 can therefore rotate the rotatable shaft 412 to simultaneously move the syringe plungers 422 a,b.

The rotation of the rotatable shaft 412 can be detected by the encoder 412 a. In the embodiment shown, the encoder 412 a is a position sensor that detects the rotation position of the rotatable shaft 412. The encoder 412 generates a signal (e.g., electrical) that is communicated to a controller (described with reference to FIGS. 10a-10b ). Using the signal provided by the encoder 412, the controller can precisely and accurately dispense fluid from the dual syringe fluid pump 410, as will be discussed in more detail in the following.

FIGS. 10a and 10b show schematic representations of the dual syringe fluid pump 400 according to an embodiment. The dual syringe fluid pump 400 includes the motor 410 which is coupled to the syringes 420 a,b. Although not shown for clarity, the syringe plungers 422 a,b are in the syringes 420 a,b. The rotation direction of the rotatable shaft 412 is indicated by an arrow in shown in the motor 410. The arrow in FIG. 10a indicates indicates that the rotatable shaft 412 is rotating in a direction with an axis oriented, using the right hand rule, towards the syringe plungers 420 a,b. The arrow in FIG. 10b indicates the rotatable shaft 412 is rotating in an opposite direction.

The direction of the fluid flow dispensed from and aspirated into the syringes 420 a,b is shown by arrows proximate the valves 426. For example, the arrow proximate the first syringe outlet valve 426 ao indicates that the fluid is dispensed from the first syringe 420 a. The arrow proximate the second syringe inlet valve 426 bi shown in FIG. 10a indicates that fluid is being aspirated into the second syringe 420 b. FIG. 10a shows that the syringe plungers 122 a,b 222 a,b dispenses fluid from the first syringe 420 a via the outlet valve 426 ao and aspirates fluid into the second syringe 420 b via the inlet valve 426 bi. The first syringe inlet valve 426 ai and the second syringe outlet valve 426 bo are shown as closed due to the fluid pressure in the syringes 420 a,b. In FIG. 10b , the syringe plungers 422 a,b are shown as moving in directions opposite the directions shown in FIG. 10 a.

In operation, the dual syringe fluid pump 100-400 dispenses fluid from the first syringe 120 a-420 a and the second syringe 120 b-420 b. The fluid can be supplied to the syringes 120 a,b-420 a,b by the fluid source 370, 470 described with reference to FIGS. 8a -10 b. The motor 110-410 can rotate the rotatable shaft 112-412 to dispense fluid from the first syringe 120 a-420 a while simultaneously aspirating fluid from the fluid source 370, 470 into the second syringe 120-420 b. The motor 110-410 can also rotate the rotatable shaft 112-412 to aspirate fluid into the first syringe 120 a-420 a from the fluid source 370, 470 while simultaneously dispensing fluid from the second syringe 120 b-420 b.

The fluid, being dispensed from one of the syringes 120 a,b-420 a,b while the other is aspirating fluid, flows from the fluid supply port 390, 490 in a substantially continuous manner. For example, even though there are two syringes 120 a,b dispensing fluid in an alternating manner, one of the syringe plungers 122 a,b-422 a,b is dispensing fluid to the fluid supply conduit 390, 490. The syringes 120-420 also do not dispense fluid at the same time. For example, the syringe plungers 122 a,b-322 a,b described with reference to FIGS. 1-9 are coupled to distal ends of the shaft 112, 212. The motor 110-310 can therefore move the syringe plungers 122 a,b-322 a,b in opposite directions. Similarly, the motor 410 described with reference to FIGS. 9-10 b is coupled to the syringe plungers 422 a,b via a coupler 412 b that can simultaneously move the syringe plungers 422 a,b in opposite directions. Since the first syringe plunger 122 a-422 a and the second syringe plunger 122 b-422 b move in opposite directions, the fluid is not dispensed from the first syringe 120 a-420 a at the same time as the second syringe 120 b-420 b.

The embodiments described above provide a dual syringe fluid pump 100-400. As explained above the dual syringe fluid pump 100-400 can simultaneously move syringe plungers 122 a,b-422 a,b to dispense fluids from a first syringe 120 a-420 a and aspirate fluid into a second syringe 120 b-420 b. This simultaneous movement reduces the complexity of the dual syringe fluid pump 100-400 over prior art dual syringe fluid pumps. In addition, having two syringes 120 a,b-420 a,b allows for the fluids to be dispensed precisely and accurately as well as continuously. For example, the displacement length of the syringe plungers 120 a,b-420 a,b can, for example, be controlled by sensors 320 as,bs that detect when the syringe plungers 120 a,b-420 a,b have moved to their fully dispensed or aspirated positions. This allows the displacement length of the syringe plungers 122 a,b-422 a,b to be controlled so desired amounts of fluids can be dispensed.

Since the dual syringe fluid pump 100-400 is less complex than prior art fluid pump designs, the precision and accuracy of the amount of fluid dispensed by the dual syringe fluid pump 100-400 is repeatable over a large number of cycles. The design of the dual syringe fluid pump 100 described with reference to FIGS. 1-5 c is even less complex by providing an interfaced profile that is adapted to prevent the rotation of the syringe plunger 122 a,b. For some applications, the interfaced profile can eliminate the need for additional or alternative constraints 252 that also limit the rotation of the syringe plungers 222 a,b described with reference to FIGS. 6-7. Depending on the application, the constraints 252 or the shaped profile plungers 122 a,b may be preferred.

The dual syringe fluid pump 100-400 is also compact. For example, the dual syringe fluid pump 100-300 with the through axis configuration can have a narrow profile. The through axis configuration can also have a profile more narrow than the dual syringe fluid pump 400 having the side motor 410 configuration. However, the dual syringe fluid pump 400, with the motor 410 on one side, can fit into a cube shaped envelope. The preferred configuration can depend on the available envelope in which the dual syringe fluid pump 100-400 is employed.

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the present description. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the present description. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the present description.

Thus, although specific embodiments are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the present description, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other dual syringe fluid pumps, and not just to the embodiments described above and shown in the accompanying figures. Accordingly, the scope of the embodiments described above should be determined from the following claims. 

We claim:
 1. A dual syringe fluid pump (100, 200, 300, 400) comprising: a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412); a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) coupled to the rotatable shaft (112, 212, 312, 412); and a second syringe (120 b, 220 b, 320 b, 420 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) coupled to the rotatable shaft (112, 212, 312, 412); wherein the motor (110, 210, 310, 410) rotates the rotatable shaft (112, 212, 312, 412) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b); and at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) is adapted to convert a rotation of the rotatable shaft (112, 212, 312, 412) to a linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b).
 2. The dual syringe fluid pump (100) of claim 1 wherein at least one of the syringes (120 a,b) further comprises a barrel (124 a) with a center bore (124 cb) having a profile that prevents rotation of the at least one of the syringe plungers (122 a,b) to convert the rotation of the rotatable shaft (112) to the linear movement of the at least one of the syringe plungers (122 a,b).
 3. The dual syringe fluid pump (200) of claim 1 further comprising a constraint (252) and an aperture (225) in the syringe plunger (222 a) wherein the constraint (252) is coupled to the motor (210) and slidably coupled to the aperture (225) to prevent a rotation of the at least one of the syringe plungers (222 a,b) such that rotation of the rotatable shaft (212) is converted to the linear movement of at least one of the syringe plungers (222 a,b).
 4. The dual syringe fluid pump (100, 200, 300, 400) of claim 1 wherein the motor (110, 210, 310, 410) is further adapted to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) and dispense fluid from the second syringe (120 b, 220 b, 320 b, 420 b).
 5. The dual syringe fluid pump (100, 200, 300, 400) of claim 1 wherein at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) further comprises: a first valve (126 ai,bi 226 ai,bi 326 ai,bi 426 ai,bi) adapted to allow fluid to flow into the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b); and a second valve (126 ao,bo, 226 ao,bo, 326 ao,bo, 426 ao,bo) adapted to allow fluid to flow out of the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b).
 6. The dual syringe fluid pump (100) of claim 1 wherein: the first syringe plunger (122 a) is coupled to a first end of the rotatable shaft (112); the second syringe plunger (122 b) is coupled to a second end of the rotatable shaft (112); and the rotatable shaft (112) extends through the motor (110) from the first syringe (120 a) to the second syringe (120 b).
 7. The dual syringe fluid pump (100) of claim 1 wherein the rotatable shaft (112) rotates coaxially with the linear movement of at least one of the syringe plungers (122 a,b).
 8. The dual syringe fluid pump (400) of claim 1 further comprising a coupler (412 b) coupled to the rotatable shaft (412) wherein the rotatable shaft (412) is adapted to rotate the coupler (412 b) to move the first syringe plunger (412 a) to dispense fluid from the first syringe (420 a) and move the second syringe plunger (422 b) to aspirate fluid into the second syringe (420 b).
 9. A method of forming a dual syringe fluid pump (100, 200, 300, 400), comprising: forming a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412); forming a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) and coupling the first syringe plunger (122 a, 222 a, 322 a, 422 a) to the rotatable shaft (112, 212, 312, 412); forming a second syringe (120 b, 220 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) and coupling the second syringe plunger (122 b, 222 b, 322 b, 422 b) to the rotatable shaft (112, 212, 312, 412); and adapting the motor (110, 210, 310, 410) to rotate the rotatable shaft (112, 212, 312, 412) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b); and adapting at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) to convert a rotation of the rotatable shaft (112, 212, 312, 412) to a linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b).
 10. The method of forming the dual syringe fluid pump (100) of claim 9 wherein the forming the at least one of the syringes (120 a,b) further comprises forming a barrel (124 a) with a center bore (124 cb) having a profile that prevents rotation of the at least one of the syringe plungers (122 a,b) to convert the rotation of the rotatable shaft (112) to the linear movement of the at least one of the syringe plungers (122 a,b).
 11. The method of forming the dual syringe fluid pump (200) of claim 9 further comprising: forming a constraint (252); forming an aperture (225) in the syringe plunger (222 a); coupling the constraint (252) to the motor (210); and slidably coupling the constraint (252) to the aperture (225) to prevent a rotation of the at least one of the syringe plungers (222 a,b) such that rotation of the rotatable shaft (212) is converted to the linear movement of at least one of the syringe plungers (222 a,b).
 12. The method of forming the dual syringe fluid pump (100, 200, 300, 400) of claim 9 further comprising adapting the motor (110, 210, 310, 410) to simultaneously move the first syringe plunger (122 a, 222 a, 322 a, 422 a) and the second syringe plunger (122 b, 222 b, 322 b, 422 b) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) and dispense fluid from the second syringe (120 b, 220 b, 320 b, 420 b).
 13. The method of forming the dual syringe fluid pump (100, 200, 300, 400) of claim 9 wherein the forming the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b) further comprises: forming and adapting a first valve (126 ai,bi 226 ai,bi 326 ai,bi 426 ai,bi) to allow fluid to flow into the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b); and forming and adapting an second valve (126 ao,bo, 226 ao,bo, 326 ao,bo, 426 ao,bo) to allow fluid to flow out of the at least one of the syringes (120 a,b 220 a,b 320 a,b 420 a,b).
 14. The method of forming the dual syringe fluid pump (100, 200, 300) of claim 9 further comprising: coupling the first syringe plunger (122 a, 222 a, 322 a) to a first end of the rotatable shaft (112, 212, 312); coupling the second syringe plunger (122 b, 222 b, 322 b) to a second end of the rotatable shaft (112, 212, 312); and extending the rotatable shaft (112, 212, 312) through the motor (110, 210, 310) from the first syringe (120 a, 220 a, 320 a) to the second syringe (120 b, 220 b, 320 b).
 15. The method of forming the dual syringe fluid pump (100, 200, 300, 400) of claim 9 further comprising adapting the rotatable shaft (112, 212, 312, 412) to rotate coaxially with the linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 b, 422 b).
 16. The method of forming the dual syringe fluid pump (400) of claim 9 further comprising: forming and coupling a coupler (412 b) to the rotatable shaft (412); and adapting the rotatable shaft (412) to rotate the coupler (412 b) to move the first syringe plunger (422 a) to dispense fluid from the first syringe (420 a) and move the second syringe plunger (422 b) to aspirate fluid into the second syringe (420 b).
 17. The method of forming the dual syringe fluid pump (100, 200, 300, 400) of claim 9 further comprising selecting a motor (110, 210, 310, 410) rotation to a syringe plunger (122 a,b 222 a,b 322 a,b 422 a,b) displacement ratio.
 18. A method of using a dual syringe fluid pump (100, 200, 300, 400), the method comprised of: providing a dual syringe fluid pump (100, 200, 300, 400) comprised of: a motor (110, 210, 310, 410) with a rotatable shaft (112, 212, 312, 412); a first syringe (120 a, 220 a, 320 a, 420 a) with a first syringe plunger (122 a, 222 a, 322 a, 422 a) coupled to the rotatable shaft (112, 212, 312, 412); and a second syringe (120 b, 220 b, 320 b, 420 b) with a second syringe plunger (122 b, 222 b, 322 b, 422 b) coupled to the rotatable shaft (112, 212, 312, 412); providing fluid from a fluid source (370, 470) to the first syringe (120 a, 220 a, 320 a, 420 a) and the second syringe (120 b, 220 b, 320 b, 420 b); rotating the rotatable shaft (112, 212, 312, 412) with the motor (110, 210, 310, 410); and converting the rotation of the rotatable shaft (112, 212, 312, 412) to a linear movement of at least one of the syringe plungers (122 a,b 222 a,b 322 a,b 422 a,b) to dispense fluid from the first syringe (120 a, 220 a, 320 a, 420 a) while simultaneously aspirating fluid into the second syringe (120 b, 220 b, 320 b, 420 b) from the fluid source (370, 470).
 19. The method of using the dual syringe fluid pump (100, 200, 300, 400) of claim 18 further comprising rotating the rotatable shaft (112, 212, 312, 412) to aspirate fluid into the first syringe (120 a, 220 a, 320 a, 420 a) from the fluid source (370, 470) while simultaneously dispensing fluid from the second syringe (120 a, 220 b, 320 b, 420 b).
 20. The method of using the dual syringe fluid pump (100, 200, 300, 400) of claim 18 further comprises dispensing fluid from the first syringe (120 a, 220 a, 320 a, 420 a) and the second syringe (120 b, 220 b, 320 b, 420 b) to a fluid supply conduit (390, 490) in a substantially continuous fluid flow. 